Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
For Doubtful Receivables [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		$ 110		$ 148	$ 121
Valuation Allowances and Reserves, Charged to Cost and Expense		24		53	65
Valuation Allowances and Reserves, Charged to Other Accounts		2	[1]	8	0	[1]
Deductions from reserves	[2]	42		99	38
Balance at end of year		94		110	148
Other Investments and Noncurrent Receivables [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		477		454	467
Valuation Allowances and Reserves, Charged to Cost and Expense		108		62	39
Valuation Allowances and Reserves, Charged to Other Accounts		0		0	0
Deductions from reserves		91		39	52
Balance at end of year		494		477	454
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		1,106		1,112	1,399
Valuation Allowances and Reserves, Charged to Cost and Expense		67		126	214
Valuation Allowances and Reserves, Charged to Other Accounts		0		0	0
Deductions from reserves		173		132	501
Balance at end of year		$ 1,000		$ 1,106	$ 1,112

[1] Additions to reserves for doubtful receivables charged to other accounts were classified as "Accounts and notes receivable - Other" in the consolidated balance sheets. These reserves relate to the Company's sale of trade accounts receivable. Anticipated credit losses in the portfolio of receivables sold are used to fair value the Company's interests held in trade accounts receivable conduits. See Notes 12 and 16 to the Consolidated Financial Statements for further information.

[2] Deductions represent notes and accounts receivable written off, credits to profit and loss and other miscellaneous items.